(noun) A person, thing, or event that prevents you from taking a much needed shit, and may or may not consequently cause you to shit in your pants. May also be used as a verb (shitblock). The person could be a cop who pulls you over for speeding - you were speeding because you had to shit so bad. It could also be an annoyingguy or girl at a party who stops you to make a bad joke, or, for those in grade school or highschool, the teacher who will not let you use the restroom.
Dan was being quite the shitblocker today - I told him I had to use a restroom and that it was an emergency, but he just wouldn't let me go.
Man you got shitblocked today when that cop pulled you over for speeding.
When you getblocked by an extremely hot individual from doing something you want.
Susan: I want to go lay out by the pool but there are two athletic girls out there showing off their bikini body's.
Spencer: You just got hotblocked girlfriend!
Susan: What's that?
Spencer: It's like getting cockblocked but the pool is like the person you want and the hot girls are like a big cock.